Anionic N-heterocyclic carbenes derived from sydnone imines such as molsidomine. Trapping reactions with selenium, palladium, and gold

The sydnone imines Molsidomine and 5-(benzoylimino)-3-(2-methoxyphenyl)-1,2,3-oxadiazolium-2-ide gave anionic N-heterocyclic carbenes on deprotonation at C4 which were trapped as methylated selenium adducts, gold complexes (X-ray analysis) as well as palladium complexes (X-ray analysis). The 13C NMR resonance frequencies of the carbene carbon atom are extremely shifted upfield and appear at δ = 142.1 ppm (Molsidomine carbene) and δ = 159.8 ppm (sydnone imine carbene). The Pd complexes were applied as catalysts in Suzuki-Miyaura and Sonogashira-Hagihara cross-coupling reactions.

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